A series of 30 'feathers', covered in madapollam cotton were attached aft of the spar, and were able to individually bend and twist as the wings were flapped.
[2] The wings could be flapped through an arc of 30° dihedral to 10° anhedral, via a parallelogram structure which the pilot could operate using leg and arm power, with a rowing-like action.
[1][2] Design of the ornithopter began in February 1958, with Hartman seeking advice from a number of aviation organisations and consultants.
Construction commenced in August, with the work being undertaken by the glider constructor Don Campbell of Hungerford, Berkshire.
During a subsequent towed flight, conducted on Wednesday, 4 November, at an altitude of 30 ft (9.1 m), Hartman experienced control difficulties due to a 7 mph (11 km/h) crosswind, landed heavily and incurred a ground loop, which damaged the port wing.